(1) Field of the Invention
This invention relates to pulse combustion devices, and more particularly to pulsejet engines and hybrid pulse combustion and turbine engines.
(2) Description of the Related Art
Diverse pulse combustion technologies exist. Pulse detonation engines (PDE's) represent areas of particular development. In a generalized PDE, fuel and oxidizer (e.g. oxygen-containing gas such as air) are admitted to an elongate combustion chamber at an upstream inlet end, typically through an inlet valve as a mixture. Upon introduction of this charge, the valve is closed and an igniter is utilized to detonate the charge (either directly or through a deflagration to detonation transition). A detonation wave propagates toward the outlet at supersonic speed causing substantial combustion of the fuel/air mixture before the mixture can be substantially driven from the outlet. The result of the combustion is to rapidly elevate pressure within the chamber before substantial gas can escape inertially through the outlet. The effect of this inertial confinement is to produce near constant volume combustion as distinguished, for example, from constant pressure combustion.
Detonation ignition, however, has several disadvantages. Achieving reliable detonation imposes complexity costs. These arise from a need for close control over parameters such as pressure, temperature, fuel droplet size, and fuel distribution as well as related use of complex initiator and combustor geometry, and the addition of supplemental accelerants such as oxygen. There may be operational drawbacks including noise and vibration, high operating temperatures and pressures, and nitrous oxide emission.
PDE technology has a variety of applications. A traditional application is pulsejet engines. Certain recent applications involve use in turbine or hybrid engines. U.S. Pat. No. 6,442,930 and earlier patents identify several hybrid applications. These include uses as thrust augmentors and as replacements for conventional continuous constant pressure turbine combustors.